SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '372ca095822ff7b6a392f828e93b2d76d6bf91702c7333c61cf9f3b54ee2035d' 
  AND token = '1fQSr93HS9hcvjujEMYiOA+6uyb3YXsY3SgDICjYhlo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}